Sulfur

It is now finally settled that the global cap of 0.5 per cent for the sulphur content of the fuel oil used by ships will apply from 1 January 2020. This is a significant reduction from the current cap of 3.5 per cent and it will cut shipping SO2 emissions by nearly 80 per cent, or around 9 million tonnes per year, and prevent more than 100,000 annual premature deaths.

Discussions about restricting air pollution from international shipping started towards the end of the eighties within the International Maritime Organization (IMO), a UN body, and agreement was reached in 1997 on an air pollution annex to its MARPOL Convention. Unfortunately, this turned out to be a very feeble document with very timid requirements.

After several more years of talks but very little action, the IMO in 2008 finally agreed and unanimously adopted sulphur standards that would significantly reduce the well-documented adverse health and environmental impacts of shipping. However, a main drawback was that the new global 0.5 per cent sulphur cap was to be implemented only 12 years later, by 2020. Moreover, due to industry pressure, it was stated that the 2020 implementation date could be postponed, subject to availability of compliant fuel.

Usually industry favours international agreements, especially when it comes to sectors of a global nature, such as shipping and aviation. This is due partly to a perceived need for harmonisation, but also because it normally takes decades to settle such agreements and the standards arrived at are often set at very low levels of ambition.

With the stricter global sulphur cap now coming into force in 2020 – more than 30 years after the issue was first raised in the IMO – it is hoped that both shipping and the oil industry will embrace the IMO standards and focus their attention on establishing effective systems for compliance monitoring and enforcement.

The nature of shipping as an international business has been used as an excuse or manoeuvre to delay environmental action for much too long and it is not acceptable for the shipping industry to keep on transferring the cost of its pollution to society at large.

It must not be forgotten that the measures agreed so far in IMO for reducing emissions of nitrogen oxides (NOx) are totally inadequate and will not result in any significant reductions in total ship NOx emissions even within the next 10–15 years. Every effort must therefore be made to markedly strengthen the weak NOx emission standards, and to make them applicable to both existing and new ships.

To ensure an organised gradual phase-in of lower-sulphur fuels, to encourage the use of the best environmental techniques, and to speed up the introduction of clean and renewable fuels, the IMO standards should be complemented by economic instruments, such as emission charges.

In addition, the EU and its member states should follow the example of the United States and Canada and designate all sea areas around Europe as “full” Emission Control Areas, i.e. covering all the major air pollutants (sulphur, particulate matter and nitrogen oxides).

Shipping is also a growing source of greenhouse gases, but there is so far no agreement on capping the industry’s CO2 emissions. An IMO meeting in October agreed only to monitor ship CO2 emissions, and to delay until at least 2023 any agreement on a CO2 reduction target. A proposed review of ship energy efficiency targets was also delayed.

It should be obvious that the longer the shipping industry delays climate measures, the steeper the emission cuts will have to be to keep within the world’s rapidly shrinking carbon budget.

Implementing the global rule to restrict the sulphur content in marine fuel oil to 0.5 per cent will cut shipping SO2 emissions by nearly 80 per cent and prevent more than 100,000 annual premature deaths.

http://airclim.org/acidnews/imo-confirms-2020-date

A decision to introduce a global 0.5 per cent cap on the content of sulphur in marine fuel by 2020 was originally agreed by the United Nations International Maritime Organization (IMO) back in 2008. At the same time, it was also agreed that a review should be undertaken by 2018 in order to assess whether sufficient compliant fuel oil would be available to meet the 2020 date. If not, the date might be deferred to 2025. That review was completed this summer, and concluded that sufficient compliant fuel oil would be available to meet the fuel oil requirements by 1 January 2020.

The IMO’s fuel oil availability assessment study1 was submitted to its Marine Environment Protection Committee (MEPC), and discussed at its 70th session held in London on 24–28 October.

The current global sulphur limit for marine heavy fuel oil (HFO) is set at 3.5 per cent, which is 3,500 times higher than the limit for fuel used in cars and trucks in the EU. As a result, shipping is one of the world’s biggest emitters of sulphur dioxide (SO2), an air pollutant that causes premature deaths from lung cancer and heart and respiratory diseases as well as acidification of sensitive natural ecosystems.

According to the third IMO greenhouse gas study from July 2014, annual emissions of SO2 from international shipping amount to approximately 10.6 million tonnes, or approximately 12 per cent of global SO2 emissions from anthropogenic sources. Moreover, international shipping emits some 18.6 million tonnes of nitrogen oxides (NOx), equal to 13 per cent of global anthropogenic NOx emissions.

Although the maximum allowed sulphur content is set at 3.5 per cent, the IMO’s sulphur monitoring scheme shows that global average sulphur content for marine HFO over the last few years has actually been around 2.5 per cent. This means that in practice the new 0.5 per cent limit will cut SO2 emissions from ships running on HFO by about 80 per cent.

The effects of introducing the 0.5 per cent sulphur cap in 2020 rather than delaying it to 2025 were analysed by a group of scientists from the United States and Finland and presented in another report2 submitted to the MEPC. Some of the key findings of this study were that:

Annual SO2 emissions will be cut by 8.5–9 million tonnes between 2020 and 2025, approximately a 77 per cent reduction in overall global SO2 emissions from international shipping.

Emissions of primary particulate matter (PM) will come down by 0.76–0.81 million tonnes per year, which equals a 50 per cent reduction.

The lowered emissions will lead to significant reductions in exposure to harmful air pollutants, especially in populated coastal areas, preventing more than 100,000 premature deaths per year. It is estimated that over the five-year period a total of 570,000 premature deaths will be avoided.

More than 90 per cent of these health benefits will take place in the Asia-Pacific region, Africa and Latin America. (Because the sea areas around Europe and North America already have stricter fuel sulphur standards, they will receive only relatively small additional health benefits from the global cap.)

The decision by the IMO to confirm 2020 as the implementation date for the 0.5 per cent global sulphur cap was taken by consensus, but it was certainly not uncontroversial. For example, oil industry associations led by IPIECA and shipping companies represented by BIMCO had sponsored the production of a separate fuel availability study, which was also submitted to the MEPC.

The official IMO report analysed three different demand scenarios – a base case as well as a low (-12%) and a high (+14%) demand case – and found that in all scenarios the refinery sector will be able to supply sufficient quantities of low-sulphur fuel from 2020 to meet the demand. On the other hand, while the report sponsored by industry acknowledged that the refining industry could meet the fuel volumes needed by 2020, it also stated that sticking to 2020 would “lead to severe strains on global oil markets” and concluded that “a full-on switch to the global sulphur standard in January 2020 does not look workable.”

Apart from the very significant health and environmental benefits of the sulphur emission reductions, the fact that in 2012 the European Union had already established a 0.5 per cent sulphur limit to apply from 2020 in its territorial seas, exclusive economic zones and pollution control zones is likely to have had quite some impact on the outcome of the debate. This encouraged EU countries to also argue in favour of 2020 as the implementation date for the global cap, and they were supported by among others the United States and Japan.

Commenting on the outcome, Bill Hemmings, shipping director at Transport & Environment, said: “This is a landmark decision and we are very pleased that the world has bitten the bullet and is now tackling poisonous sulphuric fuel in 2020. This decision reduces the contribution of shipping to the world’s air pollution impact from about 5 per cent down to 1.5 per cent and will save millions of lives in the coming decades. Now the focus should shift towards implementing this decision, which is a big issue since it’s not yet clear who should police ships on the high seas, and how.”

IMO Secretary-General Kitack Lim also welcomed the decision. “The reductions in SO2 emissions resulting from the lower global sulphur cap are expected to have a significant beneficial impact on the environment and on human health, particularly that of people living in port cities and coastal communities, beyond the existing emission control areas,” Mr. Lim said.

Further work to ensure effective implementation of the 2020 global sulphur cap will continue in the IMO’s Sub-Committee on Pollution Prevention and Response (PPR), which has it next meeting in January 2017.

IMO regulations governing sulphur emissions from ships are included in Annex VI to the International Convention for the Prevention of Pollution from Ships (MARPOL Convention). Under the new global cap, from 1 January 2020 ships will have to use fuel oil on board with a sulphur content of no more than 0.5 per cent, as compared to the current limit of 3.5 per cent that has been in effect since 1 January 2012. Fuel oil used on board includes use in main and auxiliary engines and boilers.

Ships can meet the requirement by using lower-sulphur compliant fuel oil or other types of fuel, such as liquefied natural gas (LNG) or methanol. Alternatively, ships can meet the sulphur emission requirements by using approved exhaust gas cleaning systems (scrubbers), which remove the sulphur emissions before they are released into the atmosphere. The new global 0.5 per cent cap will not change the 0.1 per cent sulphur limit that has applied since 1 January 2015 in Sulphur Emission Control Areas (SECA) established by the IMO.

The authors of a critical report that analyses the impact of cruise ships on public health and the environment have launched a withering attack on the industry and the organisation that regulates it.

Researchers at Naturschutzbund Deutschland (NABU), the German NGO behind the report, claim European cruise ships are belching out 3,500 times more sulphur dioxide than land-based vehicles, thus contributing to a range of issues including climate change, air pollution and lung problems.

“The shipping sector is lagging far behind what’s going on on land [in terms of regulating emissions],” said Daniel Rieger, a researcher at NABU. “Air pollution from ships is damaging global climate and human health.”

Rieger claims the International Maritime Organisation (IMO), which regulates shipping, could be doing more to tackle pollution caused by the cruise industry.

In most countries, he says, the maximum permitted sulphur emissions for land-based vehicles is capped at 10 parts per million (0.001 per cent); however, thanks to the IMO, the cruise industry has a more lenient limit of 3.5 per cent, which allows operators to use “cheap and dirty” heavy fuel oil.

“[The IMO] works so slow that we have to wait at least 10 or 20 years more until effective regulation will be in place,” said Rieger.

That’s not strictly true: last month the IMO announced new legislation that will slash sulphur emissions for vessels from 3.5 per cent to 0.5 per cent, though it won’t come into effect until 2020.

“Ships are subject to quite clear, quite stringent requirements with regards to their emissions and last month these were tightened still further,” said Lee Adamson, a spokesperson for the IMO.

“I have seen various comparisons done with different transport modes and what sometimes gets overlooked is that a ship is a very big unit and that it performs a very large amount of what you might call transport work.”

NABU believes the new IMO regulation does not go far enough and that cruise lines fall back on scrubbing technology to “clean” exhaust gasses rather than replace heavy fuel oil.

“What a scrubber does, technically, is spray some water on the exhaust,” explained Rieger. “The fallout is then washed into the open sea. Scrubbers just shift the problem from the air to the ocean, which, from an environmental perspective, is not the proper solution.”

NABU claims that while a handful of European cruise lines are going beyond what is legally required of them, the majority are not.

“Some are starting to take action voluntarily,” said Rieger, who helped compile a ranking system for European cruise ships. “We wanted to highlight the good guys.”

NABU rated European cruise vessels out of four, awarding a point for every measure the cruise line was taking to mitigate the ship’s impact on the environmental.

The vessels were assessed on the type of fuel they use, whether they are fitted with catalysts and particulate filters and whether they use alternative power sources when in ports. Half a point was awarded for ships that switched to cleaner fuels in Arctic waters.

The AIDAprima, flagship of AIDA Cruises, came out on top with a score of three. “It’s going beyond what is required legally,” said Rieger.

However, of the 55 European vessels assessed by NABU, 44 scored zero, including three ships operated by Royal Caribbean International.

Responding to the report, the cruise line’s managing director for UK and Ireland, Stuart Leven, told Telegraph Travel: “Royal Caribbean’s commitment to best environmental practices is fundamental to how we do business.

“We meet or exceed all environmental laws and regulations and our continuous improvement in performance is evidence of our seriousness in this area.”

Last month Royal Caribbean announced a new class of ship that will be powered by liquefied natural gas and employ fuel cell technology, which the company claims will usher in a new era of environmentally friendly cruising.

“These ships are set to be delivered in 2022 and 2024 and their green technologies will help our steady progress on increased energy efficiency and reduced emissions that will see us continue to raise the bar on environmental stewardship now and in years to come,” said Leven.

TUI Group told Telegraph Travel that it was working to improve the environmental friendliness of its cruise ships.

“These efforts include substantial investments in technology to minimize emissions for every new ship of our fleet,” said a spokesperson.

“The NABU ranking focuses on a very narrow set of technical solutions for reducing emissions. However, there are more ways to improve the environmental impact of cruise ships. The ranking does not reflect these manifold efforts.”

NABU admits its ranking system is simplistic, but maintains that it gives holidaymakers an opportunity to make informed decisions about what cruise ships they should take.

“If you would like to go on a cruise vacation and you’re interested in the environment and health you should have the opportunity to choose an operator that is taking care of this,” said Rieger.

National scheme for control areas excluded special administrative region, but local government looks to opt in from 2019

Ships plying the Pearl River Delta, including Hong Kong waters, will have to use cleaner fuel as a part of one of three new national emissions control areas, beginning 2019, the Post has learned.

This follows calls by experts and industry insiders to extend the city’s mandatory fuel switch-at-berth regulation one step further to cover its waters, falling in line with new mainland measures.

The mainland’s Ministry of Transport drew up three emissions control areas – the Pearl River Delta, Yangtze River Delta and the Bohai Economic Rim – in December.

Under that plan, all marine vessels will have to switch to low sulphur fuel while in Chinese waters, regardless of whether they are berthed, unlike Hong Kong’s current law, which is limited to berthed ships. The emissions control areas (ECAs) are pencilled to take effect in January 2019.

The ministry’s edict excludes Hong Kong and Macau from the ECA, but a spokesman for the Environmental Protection Department last night confirmed Hong Kong would be part of it.

“Hong Kong … will collaborate with the relevant mainland authorities to put the ECA in place,” a spokesman told the Post.

Simon Ng Ka-wing, chief research officer at public policy think tank Civic Exchange welcomed the move, as the discrepancy between Hong Kong and the mainland means ships entering Hong Kong can burn cheaper and dirtier fuel until they berth.

“If the cost difference is big enough, ships will switch back to burning a cheaper fuel for the one to two hours until they get to a berth in Hong Kong,” said Ng.

But he questioned how and if the city would comply with emissions targets set by the ministry under “one country, two systems”.

Hong Kong’s fuel-switch law, which came into effect exactly one year ago today, requires ocean-going vessels calling at the city to switch to fuels with less than 0.5 per cent sulphur at berth. About a tenth of all port calls were already doing so voluntarily -before in came into effect.

Similar measures will go in place in Shenzhen this year.

Ng suggested Hong Kong consider pushing the bar further for the region by requiring a stricter fuel target of 0.1 per cent sulphur – a standard that emissions control areas in the US and Europe have.

Arthur Bowring, managing director of the Shipowners Association, supported tighter fuel standards. He said: “It makes no sense for ships to have to change to a distillate fuel when entering Chinese waters, be able to switch back to dirtier fuel when in Hong Kong waters, and then to switch back to distillate after passing through Hong Kong.

“Hong Kong needs to have its legislation ready so that it is able to bring it into force when the requirement enters into force in [the Pearl River Delta].”

Bowring backed a tighter 0.1 per cent fuel requirement but hoped the supply of those fuels at Asian ports would improve. The department said tightening the standard was “impracticable” due the lack of regional availability.

Since the 1990s shipping, along with power generation, has been the largest contributor of toxic sulphur dioxide emissions in Hong Kong.

The department said data showed sulphur concentrations in Kwai Chung, Tsuen Wan and Sham Shui Po were “30 to 50 per cent lower” in the last 11 months than they were in the preceding period.
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Source URL: http://www.scmp.com/news/hong-kong/health-environment/article/1983720/hong-kong-join-mainland-chinas-fuel-emissions-plan

At full power the Harmony of the Seas’ two 16-cylinder engines would each burn 1,377 US gallons an hour of some of the most polluting diesel fuel in the world. Photograph: Peter Nicholls/Reuters

This article is the subject of a legal complaint made on behalf of Royal Caribbean International

When the gargantuan Harmony of the Seas slips out of Southampton docks on Sunday afternoon on its first commercial voyage, the 16-deck-high floating city will switch off its auxiliary engines, fire up its three giant diesels and head to the open sea.

But while the 6,780 passengers and 2,100 crew on the largest cruise ship in the world wave goodbye to England, many people left behind in Southampton say they will be glad to see it go. They complain that air pollution from such nautical behemoths is getting worse every year as cruising becomes the fastest growing sector of the mass tourism industry and as ships get bigger and bigger.

The Harmony, owned by Royal Caribbean, has two four-storey high 16-cylinder Wärtsilä engines which would, at full power, each burn 1,377 US gallons of fuel an hour, or about 66,000 gallons a day of some of the most polluting diesel fuel in the world.

In port, and close to US and some European coasts, the Harmony must burn low sulphur fuel or use abatement technologies. But, says Colin MacQueen, who lives around 400 yards from the docks and is a member of new environment group Southampton Clean Air, the fumes from cruise liners and bulk cargo ships are “definitely” contributing to Southampton’s highly polluted air.

“We can smell, see and taste it. These ships are like blocks of flats. Sometimes there are five or more in the docks at the same time. The wind blows their pollution directly into the city and as far we can tell, there is no monitoring of their pollution. We are pushing for them to use shore power but they have resisted.”

“The liners pollute, but the road traffic that they and the cargo ships generate is also huge,” he adds.

Royal Caribbean, the US owners of the Harmony of the Seas, said that the latest and most efficient pollution control systems were used and that the ship met all legal requirements.

Industry body Cruise Lines International Association (CLIA) added that companies had “invested significantly over the last decade to develop new technologies to help reduce air emissions”.

But marine pollution analysts in Germany and Brussels said that such a large ship would probably burn at least 150 tonnes of fuel a day, and emit more sulphur than several million cars, more NO2 gas than all the traffic passing through a medium-sized town and more particulate emissions than thousands of London buses.

According to leading independent German pollution analyst Axel Friedrich, a single large cruise ship will emit over five tonnes of NOX emissions, and 450kg of ultra fine particles a day.

Bill Hemmings, marine expert at Brussels-based Transport and Environment group said: “These ships burn as much fuel as whole towns. They use a lot more power than container ships and even when they burn low sulphur fuel, it’s 100 times worse than road diesel.”

“Air pollution from international shipping accounts for around 50,000 premature deaths per year in Europe alone, at an annual cost to society of more than €58bn [ $65bn],” says the group on its website.

Daniel Rieger, a transport officer at German environment group Nabu, said: “Cruise companies create a picture of being a bright, clean and environmentally friendly tourism sector. But the opposite is true. One cruise ship emits as many air pollutants as five million cars going the same distance because these ships use heavy fuel that on land would have to be disposed of as hazardous waste.”

Nabu has measured pollution in large German ports and found high concentrations of pollutants. “Heavy fuel oil can contain 3,500 times more sulphur than diesel that is used for land traffic vehicles. Ships do not have exhaust abatement technologies like particulate filters that are standard on passenger cars and lorries,” says Rieger.

Southampton, which has Britain’s second largest container port and is Europe’s busiest cruise terminal, is one of nine UK cities cited by the World Health Organisation as breaching air quality guidelines even though it has little manufacturing.

“Up to five large liners a day can be berthed in the docks at the same time, all running engines 24/7, said Chris Hinds, vice chair of the Southampton docks watchdog group WDCF. “Pollution from the port is leading to asthma and chest diseases. We are now seeing more, bigger liners but also very large bulk cargo ships.”

According to CLIA, the cruise ship industry is now one of the fastest growing sectors in the mass tourism market, with 24 million passengers expected to sail in 2016, compared to 15 million in 2006 and just 1.4 million in 1980.

“The industry shows no signs of slowing down. It generated $119.9bn (£83bn) in total output worldwide in 2015, supporting 939,232 full-time equivalent jobs,” said a spokesman.

“The luxury sector is seeing the most amazing growth that it has ever seen in its history,” said Larry Pimentel, president of Azamara club cruises.

• This article was amended on 23 May 2016. An earlier version said the Harmony of the Seas had three 16-cylinder engines which, if running at full power, would burn 96,000 US gallons of fuel a day. It has two such engines which together would burn about 66,000 US gallons of fuel a day if running at full power, and is understood to have four 12 cylinder engines. The article also said the ship must burn low-sulphur fuel in port and close to some coasts; it can also use abatement technologies to meet emissions guidelines.

Air quality in coastal areas improved significantly in 2015 after stricter sulphur limits for marine fuels were introduced in the North Sea and the Baltic Sea.

In several countries bordering the North Sea and the Baltic Sea, concentrations of sulphur dioxide (SO₂) have come down by 50 per cent or more in 2015 compared to previous years, according to a recent study by the Dutch research consultancy CE Delft conducted on behalf of the German environmental group NABU (Nature and
Biodiversity Conservation Union).

The study has investigated the experiences of the first year of applying stricter marine fuel sulphur standards in the Sulphur Emission Control Area (SECA) covering the North Sea and the Baltic Sea. It focussed on air quality, socio-economic effects, impacts on business, and on compliance and enforcement.

As from 1 January 2015 the maximum sulphur content of marine fuels used in SECAs was reduced by 90 per cent, from 1.0 to 0.1 per cent. The resulting health benefits of better air quality were estimated to amount to between €4.4 and 8 billion.

This can be compared to the cost to the maritime sector of moving to low-sulphur marine gas oil (MGO) in the North Sea and the Baltic Sea, which was estimated at €2.3 billion.

The researchers conclude that the health benefits of lower emissions of SO₂ and particulate matter (PM) were between 1.9 and 3.5 times higher than the increase in fuel costs, which means that the benefits of introducing the new regulations clearly outweighed the cost.

Before its implementation, there were industry concerns that the stricter fuel standard would significantly increase fuel costs and that there would be problems with the availability of low sulphur fuels. There were also concerns about impacts on the industry, such as closures of companies or services, and potential shifts towards road transport. The lack of effective surveillance schemes to ensure compliance and enforcement were also subject to debate.

The study found that the availability of MGO has proven to be sufficient and that the price of MGO actually decreased – the latter mainly as the result of reduced oil prices in general. However, the MGO price decreased more sharply than the price of heavy fuel oil (HFO) and automotive diesel. In fact, by the end of 2015, the price of 0.1 per cent sulphur MGO was at the same level as the price of high-sulphur HFO was at in the beginning of 2015.

No significant shifts towards road transport were found for RoRo transport, which is regarded as the market segment that is most sensitive to a modal shift.

Moreover, no company or service closures, nor any decrease in cargo turnover in Northern European ports, was found that could be clearly linked to the introduction of the stricter sulphur standard.

Interestingly, some shipping companies reported a financial record year for the year 2015 and established new services.

According to data for 2015 from the European Maritime Safety Agency (EMSA), between three and nine per cent of the ships were non-compliant in the Baltic Sea and North Sea, respectively. It should be noted that countries typically use a margin of up to 20 per cent above the legal threshold during control in ports for reporting deficiencies and 50 per cent for applying sanctions.

It is believed that the rate of noncompliance on the open seas might be significantly higher, but the limited data available does not allow any firm conclusions.

More and better data are needed in order to estimate the actual compliance rate on the open seas. In addition, fuel sampling needs to be intensified in 2016 in order to meet the required 30–40 fuel samples per 100 administrative inspections, as required by EU legislation.

It is recommended that there should be further development of monitoring and control techniques, including control on the open seas, to improve the effectiveness of the inspection regime. The authors also recommend that countries apply sanctions that are proportionate to the economic benefits of non-compliance.

Ship emissions now remain the third largest source of air pollution in China, following vehicles exhaust and factory emissions.

According to the Economic Information Daily, the emission of a ship that uses fuels with 3.5% sulphur discharge is tantamount to that of 210 thousand trucks per day. The pollutants contain dozens of toxic chemicals that pose critical damage to people’s health.

Right now, China’s marine fuel quality lags behind that of major developed countries.

Industry observers suggest the establishment of an inter-regional mechanism to jointly tackle the problem.

Hong Kong is the first Chinese city to take strong actions against ship emissions, where half of air pollution was produced by marine vessels. In 2013, Hong Kong chief executive C. Y. Leung called for “green transport”, requiring vessels to use low-sulphur diesel in the Pearl River Delta ports.

Meanwhile in Shenzhen, over 100 container vessels from 15 shipping enterprises have participated in a project aiming to subsidize ships using low sulfur fuel or shore power.

In June, Chinese authorities said it was considering a new standard in regards to the country’s marine fuel quality and usage.

Last year, China rolled out its Air Pollution Action Plan, declaring a war against the country’s long-existing air pollution problem.

Sulphur pollution near one of Hong Kong’s busiest shipping lanes fell markedly in the first week of this month as a result of new regulations mandating ocean-going vessels switch to cleaner fuel, according to the Clean Air Network.

Average 24-hour concentrations of toxic sulphur dioxide (SO2) in Kwai Chung were recorded at 12 micrograms per cubic metre of air between July 1 – the day the mandate went into effect – and Tuesday.

By comparison, the average 24-hour SO2 concentration in the same period last year was 34 micrograms per cubic metre and 23 micrograms per cubic metre the year before that.

The new rule requires all ocean-bound vessels from tugboats to container ships to switch to 0.5 per cent sulphur marine fuel when berthing in the city.

Kwai Chung, which together with Tsing Yi forms Kwai Tsing district, is located near the Kwai Chung container port – the world’s fourth biggest in terms of throughput.

Previous studies have found the area to be the worst hit district in the city from ship pollution. Ships are the biggest source of SO2 in the city, followed by power generation.

In terms of roadside pollution, average levels of nitrogen dioxide, suspended particulates and ozone all dropped in the first half of the year.

But average concentrations of microscopic particulate matters suspended in the air, or PM, rose in Tuen Mun, Tung Chung, Causeway Bay and Mong Kok in the same period. Particulates can penetrate into the lungs and cause respiratory and cardiovascular problems.

All five major pollutants measured at 11 out of 15 of the city’s air quality monitoring stations exceeded the World Health Organisation’s guidelines.

Other than in Kwai Chung, Kwun Tong and Tai Po, concentrations of ozone – an indicator of regional air quality –recorded lower than average recordings at all ambient monitoring stations in the first six months of the year.

But the number of times ozone levels exceeded WHO guidelines over eight-hour periods rose at all stations in the same period.